The disclosure relates to a projector, an optical compensation method therefor, and a liquid crystal device.
Recently, liquid crystal projectors (projection-type display devices) have been in practical use as display devices for large screen displays. A light valve structure has been proposed for such projectors that has a liquid crystal device driven in a VA (Vertical Alignment) mode in which liquid crystal molecules having a negative dielectric anisotropy are vertically aligned with respect to a substrate thereof and the liquid crystal molecules are aligned horizontally by application of voltage. In addition, in order to improve the contrast level of this kind of liquid crystal projector, technology in which a phase difference plate is disposed to be tilted with respect to the liquid crystal light valve has been proposed (see, for example, Japanese Patent Application Laid-Open Publication No. 2006-11298).
By using the above-described technology, the contrast level of the liquid crystal projector can be improved as compared with where the phase difference plate is not tilted. However, when the structure disclosed in Japanese Patent Application Laid-Open Publication No. 2006-11298 is used for a liquid crystal projector, it can be difficult to obtain a sufficient contrast level due, at least in part, to the combination of the polarizing plate and the refraction element.
For example, a TAC (triacetyl cellulose) film may be used as a protection film for the polarizing plate, and this protection film has a phase difference. However, it is difficult to compensate for this using the phase difference plate.
Furthermore, when a refraction element such as a micro lens array is provided in the liquid crystal projector, a phase difference of light is generated depending on a position in which the light passes through a micro lens, and diffusion of the light further occurs. In such a case, even when a tilt angle is set to a pre-tilt of the liquid crystal, light that cannot be compensated for is included, and accordingly, the contrast level of the liquid crystal projector decreases.